OpenXML error “file is corrupt and cannot be opened.”

From time to time I ear some people saying their new web application supports data export to Excel format.

So far so good … but they don’t tell the all story … in fact almost all the times what is happening is they are exporting data to a Comma-Separated file or simply exporting GridView rendered HTML to an xls file.

Ok … it works but it’s not something I would be proud of.

So … yesterday I decided to take a look at the Office Open XML File Formats Specification (Microsoft Office 2007+ format) based on well-known technologies: ZIP and XML. read more